1. Field of the Invention
The present invention relates to a wireless receiver and a method using the same, and more particularly, to a direct sampling type wireless receiver and a method using the same that reduce nonlinearity and DC offset by using a multi-port network and a carrier frequency direct conversion method with a low sampling rate of a direct sampling method in a wireless communications receiver.
2. Description of the Related Art
Recently, with the technological development of wireless communication, various types of wireless communication technologies have been developed.
In general, the wireless communication technologies perform down conversion of RF (radio frequency) signals into IF (intermediate frequency) signals and convert the IF signals into baseband signals to restore information contained in original signals and use the restored information.
The above-described wireless communication technologies require many RF devices to perform IF down conversion and baseband conversion and need to convert both characteristics and structures of the RF devices when changing a system. Therefore, a carrier frequency direct conversion method that does not use IF down conversion has been used.
The carrier frequency direct conversion method can be easily used to change the system. However, DC offset caused by direct conversion or phase mismatch between I/Q signals may occur to cause deterioration in performance. Further, in order to convert the entire circuit used in the carrier frequency direct conversion method into a digital system, analog signals need to be converted into digital signals by using a sampling frequency that is generally equal to or higher than twice the carrier frequency.
When a usable frequency band reaches several GHz, in order to perform an analog to digital conversion operation with the high frequency that is higher than twice the carrier frequency, an apparatus that has a high sampling rate needs to be used. Since such an apparatus requires high resolution computing, the cost and volume of the apparatus increase. Therefore, it may be impossible to apply the above apparatus to the wireless communication device that is being reduced in weight, thickness, and size.
Therefore, in order to solve the above-described problems, there is a need for a wireless communication device using a new sampling method.